Nov. 27,1916 
Claviceps paspali 
403 
1915 and on June 12 in 1916, being, respectively, 29 and 22 days after 
germinating sclerotia were first found. In 1915, infected or diseased 
heads were not plentiful in the fields until about July 12. Preceding 
this date there were several days of rainy weather. In 1916, similar 
observations were made. Diseased heads became very common during 
July, following several weeks of rain. On August 1, 1916, they were 
more plentiful than since the autumn of 1914. 
In the fields the first infection of the season is doubtless carried by 
insects. Running over the ground, they are likely to rub against the 
stromatic heads, which are covered with ascospores, and, climbing up the 
grass culms to take flight, may carry ascospores to the grass flowers and 
produce infection. That infection does not take place often is evidenced 
by the fact that the disease is slow in 
getting a start after the sclerotia ger¬ 
minate. 
The infecting fungus attacks the pistil 
of the grass flower, and in a few days 
the ovary is almost entirely destroyed, 
a mass of fungus tissue filling the space 
it occupied. Plate 32, D, shows a sec¬ 
tion of the mass of fungus tissue between 
the glumes of a grass spikelet a week 
after infection. The two spots in the 
central part of the figure represent 
remnants of the grass flower. The rest 
of the central part of the section is 
homogeneous tissue, while around the 
edge are numerous tufts of hyphge stand¬ 
ing at right angles to the central mass. Figure C of Plate 32 shows 
the tufts enlarged. Each tuft contains a number of hyphge. The 
digital ends of these hyphge, or certain of them, enlarge and form 
conidia or sphacelia spores. Figure 2 shows the tip of a tuft of 
hyphge. The spores are hyalin but show granules when stained, 
oblong, about 5^ wide and 15/x long. They are produced in great abun¬ 
dance and are carried from the hyphge on which they were produced by 
a droplet of honeydew, a sticky, sweetish exudation of the fungus tissue. 
Insects of many kinds feed on this honeydew and carry infection by 
means of the spores clinging to their bodies. Hand inoculations, which 
were made by smearing honeydew containing sphacelia spores on flower 
stigmas, produced infections that were exuding honeydew and sphacelia 
spores freely within the space of a w r eek. This result was obtained 
in the case of plants kept under bell jars, and also with plants inoculated 
in the field. Sphacelia spores frequently germinate in the droplet of 
honeydew and give it a whitish appearance. 
Fig. 2. —Claviceps paspali : Tip of tuft of 
hyphae, showing the production of spha¬ 
celia spores. 
